The Maori Council's claim to the Waitangi Tribunal over water is "opportunistic" and the Government's process to define Maori rights over water is supported by a number of iwi leaders says Prime Minister John Key.

Speaking to reporters this morning, Mr Key said the council's claim that the sale of 49 per cent of Mighty River Power should be delayed until Maori water rights are defined was likely to go to court but was unlikely to delay the sale of shares in the company later this year.

While recent days have see support for the council's claim from some members of Maoridom's peak body, the Iwi Leaders Group, Mr Key said the Government had been addressing the issues around Maori rights and interests in water in discussions with iwi leaders over the last four years, "and I think that there's no merit in the case that the Maori Council is bringing."

"Most of the Maori I talk to want to see a resolution to their rights and interests and they are comfortable the process the Government is taking is the right one.

"In my view the Maori Council speaks for one group in Maori but certainly not all Maori. There are many iwi leaders who support the Government. They've been very supportive of what we've been doing over the last three or four years and they've seen that process as a much more logical and coherent process than any application by the Maori Council to the Waitangi Tribunal.

"If you want to follow the argument of the Maori Council, why wasn't that tested in 1999. when Contact Energy was sold? Why wasn't it tested when Trustpower was sold. In my view it's opportunistic."

Mr Key has repeatedly said the Government can ignore any recommendations made by the tribunal - but yesterday conceded it was almost inevitable the issue would go to the courts which could delay the partial float of Mighty River Power.

However this morning he compared the probability the sale would be delayed to chances to the "chance a meteorite will hit the Earth this afternoon".

But Labour leader David Shearer believed the sale would have to be delayed.

"I think the share price has been affected I think there could be issues around costs and who is going to meet those costs. It's going to be the taxpayer.

"New Zealanders, if these assets are to be sold, would want to have the best share price they could possibly get for these assets. With the uncertainty and risk around this, I think that's very very questionable."

Responding to questions about Mr Key's view that issues around Maori rights and interests were best addressed through ongoing discussions between iwi leaders and ministers, Mr Shearer said Mr Key should pay attention to the Waitangi Tribunal's findings which are due by the end of the month.

The tribunal was a highly respected body that had done some very good work.

"It's important and and many of its judgments have been used in subsequent cases that have gone on to the High Court."